Rajon Rondo doesn't have a good year in Chicago and he was benched recently, so that was a sign for the Cavaliers to watch his situation with the Bulls.
According to RealGM LBJ said this:
“Kay’s in the process of learning on the fly,” James said. “He’s a rookie and is going to have his mistakes and things of that nature. It’s tough on him because we’re a franchise trying to win a championship. He has to have a fast-track mind. But we don’t have a backup point guard.”
In that same article, writer Joe Vardon said this about the Cavaliers interest in Rondo/Chalmers:
The Cavaliers are monitoring Rajon Rondo’s situation with the Chicago Bulls while Mario Chalmers is also on their radar as he works his way back from a torn Achilles.
It's not impossible to see Rajon Rondo in Cleveland before the trade deadline.
If Chicago Bulls decide to trade Jimmy Butler, they will trade Rajon Rondo, as well.
With only 7.2 points and 7.1 assists, this is the worst season in his career so far. Maybe he needs a better pick and roll player (DeMarcus Cousins, Kevin Garnett), and he can find that playing with LeBron James and Kevin Love.
Rajon Rondo has a lot of energy and he can easy lead Cavaliers' 2nd lineup. Cleveland really need a backup point guard and maybe Rajon Rondo is the best option so far.
We will see if he will have a buyout or Chicago Bulls will just trade him for young players.